Delta Lupi

Delta Lupi (δ Lupi, δ Lup) is a star in the southern circumpolar constellation of Lupus. In traditional Chinese astronomy, it is "the 2nd (star) of the Cavalry Officer" (騎官二). With an apparent visual magnitude of 3.22,[2] it is the fourth-brightest star in the constellation. The distance to this star has been measured using the parallax technique, yielding an estimate of roughly 900 light-years with a 15% margin of error.[1]

δ Lupi
Location of δ Lupi (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lupus
Right ascension 15h 21m 22.32168s[1]
Declination –40° 38′ 51.0738″[1]
Apparent magnitude (V) 3.22[2]
Characteristics
Spectral type B1.5 IV[3]
U−B color index –0.910[4]
B−V color index –0.224[4]
Variable type β Cep[5]
Astrometry
Radial velocity (Rv)+0.2[6] km/s
Proper motion (μ) RA: −19.49[1] mas/yr
Dec.: −25.29[1] mas/yr
Parallax (π)3.69 ± 0.54[1] mas
Distanceapprox. 900 ly
(approx. 270 pc)
Absolute magnitude (MV)–3.1[2]
Details
Mass11.9 ± 0.2[7] M☉
Radius6.1[8] R☉
Luminosity10,000[7] L☉
Surface gravity (log g)3.86[7] cgs
Temperature22,908[7] K
Metallicity [Fe/H]–0.25 ± 0.11[9] dex
Rotational velocity (v sin i)230[10] km/s
Age15.4 ± 1.3[7] Myr
Other designations
CD −40° 9538, FK5 1402, HD 136298, HIP 75141, HR 5695, SAO 225691, UBV 13201.[11]
Database references
SIMBADdata

The spectrum of this star matches a stellar classification of B1.5 IV,[3] which indicates this star has entered the subgiant stage and is in the process of evolving into a giant star. It is radiating around 10,000 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 23,000 K, giving it a blue-white hue. This star has nearly 12 times the mass of the Sun and is roughly 15 million years old.[7]

Delta Lupi is a Beta Cephei variable star that undergoes periodic pulsations. It has a single period of variability lasting 0.1655 days, or six cycles per day.[5] This is a proper motion member of the Upper-Centaurus Lupus sub-group in the Scorpius-Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[2]

See also

References
  1. van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode:1989A&A...216...44D
  3. Hiltner, W. A.; Garrison, R. F.; Schild, R. E. (July 1969), "MK spectral types for bright southern OB stars", Astrophysical Journal, 157: 313, Bibcode:1969ApJ...157..313H, doi:10.1086/150069
  4. Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168
  5. Smolec, R.; Moskalik, P. (May 2007), "Amplitude saturation in β Cephei models", Monthly Notices of the Royal Astronomical Society, 377 (2): 645–656, arXiv:astro-ph/0702406, Bibcode:2007MNRAS.377..645S, doi:10.1111/j.1365-2966.2007.11620.x
  6. Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E
  7. Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x
  8. Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189: 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601
  9. Niemczura, E.; Daszyńska-Daszkiewicz, J. (April 2005), "Metallicities of the β Cephei stars from low-resolution ultraviolet spectra", Astronomy and Astrophysics, 433 (2): 659–669, arXiv:astro-ph/0410440, Bibcode:2005A&A...433..659N, doi:10.1051/0004-6361:20040396. Note: value taken from [m/H].
  10. Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1). Bibcode:1970CoAsi.239....1B.
  11. "del Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-01-18.
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